The killings and the coverup is the subject of a new documentary, No Stone Unturned, directed by Alex Gibney.

There shouldn’t have been much mystery about who actually pulled the trigger, or much difficulty finding them—what the gunmen left behind was “a forensic goldmine,” according to ex-investigator Jimmy Binns.

The getaway car had been sold just the day before the killings; a day later, it was found abandoned in a farmer’s field. Less than two months later, a bag with gloves, handguns, the balaclavas worn by the killers and hair all turned up.

“The cover-up,” Gibney says, with some exasperation, “was staggering in terms of its breadth and audacity—especially given the kind of evidence that was at their disposal.”

The field where the getaway car was found was never properly examined. Soil samples weren’t taken. A remarkable amount of evidence was destroyed – including the transcripts of the suspect interviews and the car which the gunmen used in the attack.

The chief investigating officer on the case went on a month’s holiday the day after the murder.

Gibney said, “We identified the likely killers, their enablers, and maybe more importantly, who covered it up.”

Massacre

The Police Ombudsman for Northern Ireland concluded that the massacre was a result of collusion between some police officers and paramilitaries.

The report identified the lead killer as "Person A" and named the village where he lived. It said he had been an officer with the Ulster Defence Regiment (UDR), and had access to confidential army and police reports before the massacre. The UDR was a British army regiment recruited only in Northern Ireland and eventually became almost 100 percent Protestant.

It said that "Person A's" fingerprints were found on confidential documents and that he was linked to Loyalist weapons found by police.

The suspect and his wife were arrested but released without charge.

The film No Stone Unturned names him as Ronald Hawthorne.

The documentary also names Gorman McMullan, from Belfast, as the driver of the getaway car and Hawthorne’s wife Hilary as allegedly implicating herself around the planning of the attack.

Hilary Hawthorne named her husband among the suspects in two calls to an anonymous phone line. The film also said she named the three men allegedly involved in the attack in an anonymous letter to a local SDLP councillor.

Police recognised her voice because she worked at a police station.

The Hawthornes live a few miles from the site of the murder and they have a cleaning and pest extermination business.

The documentary also names the suspected second gunman, Alan Taylor, who is believed to have left Northern Ireland in the late 1990s and lives in England.

The assault rifle used in the killings was one of a cache of weapons smuggled into Northern Ireland in the 1980s by yet another police informant.

These rifles were used in at least 70 murders.

As the dirty war in Northern Ireland reached a grubby conclusion, the British state made sure that those it had armed, paid and encouraged were hidden from justice.